In certain applications, such as high-power microwave sources, pulsed lasers, particle beam generators, nuclear event simulators, and directional energy weapons, and the like, it is necessary to store electrical energy for release in pulses having extremely fast rise times (e.g., .ltoreq.10 nanoseconds) and short durations (100 nanoseconds to microseconds).
High current self-sustained diffuse glow discharges are suitable for use in high voltage pulsed power applications where fast closing, high repetition rate switching is required. A schematic showing the operation of a UV light triggered glow discharge closing switch in a capacitive energy storage circuit is shown in FIG. 1. The major problems that have been encountered with this type of switch are the high impedance of the discharge and the instability of the glow discharge which leads to the formation of electrical arcs between the switch electrodes and consequently destroys the repetitive operation of the switch. The voltage waveform that appears across the switch electrodes is shown schematically in FIG. 2. The present disclosure describes gas mixtures which will lower the switch voltage V.sub.s (i.e., increase the switch efficiency) by the use of temperature modified electron attachment processes while at the same time increasing the stability of the discharge.
Accordingly, there is need for a gas mixture for use in such switches that has the capability for conducting a large amount of energy between the electrodes of a diffuse-discharge switch when the switch is in a conducting mode with a high electrical efficiency and which has a high insulating capability when the switch is in a nonconducting mode.
The physio-chemical properties required of the gas mixture to achieve high efficiency, stable discharge operation were discussed in detail for the first time in S. R. Hunter, L. G. Christophorou, J. G. Carter and P. G. Datskos, "New Concepts for High Current Self-Sustained Diffuse Discharge Closing Switches" to be published in the Proceedings of the 6th IEEE Pulsed Power Conference, Arlington, VA, June 29-July 1, 1987 (the disclosure of which is incorporated herein by reference). The stability of the glow discharge is enhanced by tailoring the electron attachment coefficient (.eta./N) and the ionization coefficient (.alpha./N) of the gas mixture in such a way that the rate of change in the electron production and loss is minimal during small perturbations of the applied electric field beyond the glow discharge operating voltage level V.sub.s.
The invention disclosed in the co-pending application by the present inventors, the disclosure of which is fully incorporated herein by reference thereto (L. G. Christophorou and S. R. Hunter, "Ternary Gas Mixtures for Diffuse Discharge Switch," U.S. Pat. No. 4,751,428 issued June 14, 1988, discusses the various gases which may be used to improve the switching stability and efficiency of room temperature diffuse discharge closing switches. The present invention is distinguished from that invention by utilizing the heat generated in the diffuse discharge to improve the efficiency of the closing switch. This is accomplished by utilizing different physio-chemical properties of the gas mixture in comparison with those described in S. R. Hunter and L. G. Christophorou, "Binary and Ternary Gas Mixtures for Use in Glow Discharge Closing Switches," U.S. patent application, Ser. No. 186,856, filed 4/27/88 the disclosure of which is fully incorporated herein by reference thereto, namely the large decrease in electron attachment with increasing gas temperature that has been observed to occur in several electronegative gases disclosed in the present disclosure.
However, increased efficiency and stability during the diffuse glow discharge is still needed to further enhance the desirable characteristics of this type of switch.